Is a triangle with 4 verts considered a quad?
Yes, it is a quad, even if two of the edges are exactly in a line. If, for example, you were to use triangulate (Ctrl + T while in Edit mode) you would find that it was split into two tris (hopefully from the bottom right point to the middle left one).

I generally find making tris into quads like this makes for a messier model, though, unless there is a reason for it. If it works with your mesh, then go for it, but if you are just doing something like this to have quads, I don't think it's a great idea (feel free to correct me if you think I'm wrong).